There are Christian old earth creationists such as Hugh Ross with a day-age theory. (http://www.reasons.org)
We need to be very careful, however, in too easily assuming that the creation has gone on according to the same principles of physics from the beginning. This may sharply limit the ability of science to frame in the manner of the creation. The young earth scientific creationists and the old earth creationists may be flirting with the same kind of errors, but from different viewpoints.
We love Hugh Ross & his wife Kathy. We have been to Hugh’s Sunday School class many times in California, and when they come to Houston, we go to hear him speak there too. I do not always agree with Hugh, even though his IQ is a trillion times higher than mine.
What is crazy, my husband doesn’t believe the world was created in 6 days as the Bible says it was. But he believes people did live hundreds of years, and that Sarah had a baby at age 80. I am right the opposite. I believe if God had wanted to He could have created the world in less than a nano second. But I don’t believe Sarah had a baby at age 80.
The good thing for us is that none of this matters. The only theological question is WHY. Not when, where, how, etc. WHY did God create us? That is the question.